Boric acid esters of 2-vinylthioethanol

ABSTRACT

Boric esters of the formula

United States Patent Naarmann et al.

BORIC ACID ESTERS OF 2- VINYLTHIOETHANOL Inventors: Herbert Naarmann,Ludwigshafen; Heinrich l-lartmann, Limburgerhof,

both of Germany Assignee: Badische Anilin- & Soda-FabrikAktiengesellschaft, Ludwigshafen/ Rhine, Germany Filed: Dec. 22, 1969Appl. No.: 887,345

U.S. Cl. ..260/462 R, 260/45.7 R, 260/79.7, 260/837 R, 260/844, 260/851,260/856, 260/870, 260/875, 260/878, 260/884,

260/DlG. 24 Int. Cl. ..C07f 5/04 Field of Search ..260/462 R 51 Oct. 10,1972 Primary Examiner-Leon Zitver Assistant Examiner-L. B. De CrescenteAttorney.lohnston, Root, O'Keeffe, Keil, Thompson & Shurtleff [57]ABSTRACT Boric esters of the formula (Cl-I CH-SCH CH -O),, B(OR),

where R represents an alkyl radical, optionally substituted, and n isequal to l, 2 or 3. The products are used as flameproofing agents forplastics materials and resins.

2 Claims, No Drawings BORIC ACID ESTERS OF Z-VINYLTHIOETHANOL Theproduction of boric esters from boric acid, boric anhydride or borichalides and substituted or unsubstituted aliphatic, cycloaliphatic andaromatic alcohols is already known (Organoboron Chemistry, Vol. I, H.Steinberg, John Wiley and Sons Inc., New York, London, Sidney, pp. 27 etseq. and pp. 155 et seq.).

Furthermore, the use of inorganic boron compounds such as boric acid,borax and trihaloborates or organic boron compounds such as sodiumhexylolglycol monoborate, borocyclo-octanes or trialkoxy boroxine forflame-proofing cellulosic materials such as paper, wood and cottonfabrics or plastics materials and resins such as polyvinyl acetate,polyisocyanates, polyesters, epoxy, melamine and phenolic resins is alsoknown (A. Vogel, Flammfestmachen von Kunststoffen, Dr. A. Huttig Verlag,Heidelberg, 1966.

Some of these compounds suffer from the disadvantage that they give offaggressive acids such as hydrogen chloride when heated or in contactwith moisture or that they are only effective in relatively largequantities and thus have an adverse effect on the mechanical propertiesof the plastics materials.

It is an object of the present invention to provide boron-containingflame-proofing agents which are effective in substantially smallerquantities and are copolymerizable with the usual monomers used in theproduction of plastics.

We have found that these advantageous properties are exhibited by boricesters of the formula (CH =CHSCH CH O),, B(OR) n where R represents anunsubstituted or substituted alkyl radical of l to 5 carbon atoms and nis equal to 1, 2 or 3.

The said compounds are boric esters of vinylthioethanol, that is,vinylthio-ethyl dialkylborate, bis(vinylthio-ethyl) alkylborate andparticularly tris(vinylthio-ethyl) borate. Suitable unsubstituted orsubstituted alkyl radicals are, for example, the methyl, ethyl, propyl,isopropyl, amyl, 2,3-dibromopropyl and 2-mercapto-ethyl groups.

The new boric esters are obtained by the methods generally used for theproduction of boric esters, that is, for example, by reactingvinylthio-ethanol and optionally other alcohols with boric acid or boricanhydride, preferably in the presence of acid catalysts such as sulfuricor hydrochloric acid, or by carrying out trans-esterification reactionsinvolving a trialkylborate and vinylthio-ethanol.

The new compounds are extremely valuable as flame-proofing agents forplastics materials such as polystyrene, polyethylene, polyvinylchloride, polyurethanes and preferably polyesters and resins such asepoxy, melamine, urea and phenolic resins. The new boric esters are usedin quantities such that the plastics or synthetic resins contain from0.1 to 2 percent by weight and preferably from 0.1 to 1 percent byweight of boron calculated on the total weight of polymer.

The new boric esters are copolymerizable with the monomers normally usedin the production of plastics materials. Where they contain more thanone C=C bond, they will additionally be suitable as cross-linkingcomponents. This makes it possible to anchor the flame-proofing agent inthe structure of the plastics material, and consequently, the exudationof the additive frequently observed when other flame-proofing agents areused, is avoided. The new materials are thus of excellent value asadditives in the production of polyester molding compositions.

In the following Examples the parts are by weight. The flame resistancetest was carried out according to a standard method in which adraught-guarded Bunsen burner flame, 6 cm long, is directed toward apolyesterlaminated wooden board, the polyester layer being 4 cm from thetip of the flame and at an angle of thereto.

According to the similar A.S.T.M. standard D 635-65 T a period of 30seconds meets the requirements of a non-burning, self-extinguishin gpolyester.

EXAMPLE 1 to 9 65 I A standard polyester was esterified by theesterification of 1 part of phthalic acid, 2 parts of maleic acid and 3parts of propylene glycol at 180 C until an acid number of 50 wasobtained. Dilution was then carried out with styrene until theproportion of polyester was 66 percent by weight and the acid number was30.

Curing was effected by a. adding 0.4 percent by weight of cyclohexanoneperoxide and 0.04 percent by weight of cobalt naphthenate and heatingfor 20 minutes at 1 10 C, or by b. adding 0.5 percent by weight ofbenzoin methyl ether and heating for 5 minutes at C in ultraviolet light(black lamp).

In each case, the percentages are calculated on the total weight ofpolyester. This standard mixture is modified by various additions of thecompounds of the invention, as set out and compared in Table 1 below.The time to ignition is the time taken for the improved wood, that is,the polyester coating to commence burning after application of theflame.

The letters L and P in the Table indicate that the polyester wassubjected to curing by light and peroxide respectively.

TABLE 1 Time to ignition in seconds, Burning Percent ASTM D time inExample Additive boron 635-65T seconds Remarks 1a None 8-10 50 P 11)None 8-10 50 L 2a H Standard mix plus 1.8% boric acid... 0.3 15-20 -20 L2 2b Standard mix plus 3.6% boric acid 0.6 10-18 -20 L 3a... Standardmix plus 1.8% tris (diehloroethyl) phosphate. 8-10 -25 L a 3l1 Standardmix plus 3.6% tr1s(dlchloroethyl) phosphate. 8-10 -20 L 4.. Standard mixplus 3% (Cllz=ClI-S-Cllz-ClIzOhB. 0.1 18 10 L 5 Standard mix plus 5%((JIIFCIL-S-Gllg-C11:0) 13. 0.15 30-34 8 L (L. Standard mix plus 10%(UlIz=C1IS- ClIz-CII2O)3B.. 0.3 33-38 5 L 7 Standard mix plus 15%(UIIFGlISGII2CH10) B 0.45 32-42 3-5 L 3". Standard mix plus 5%(CII2=CHC0O-CIIzCHzO) B 0.15 42 5 L a Standard mix plus 10%(CH2=CHC0O-CHzCHzO) B 0.3 64 3-5 L l The burning time is the mean periodfor which 5 samples continued to burn after ignition. 2 Added boric acidunevenly distributed; cloudy varmsh.

3 CI. French Pat. No. 1,437,408.

8 332 5 53m m en 23.82% 23 m awobn 3c @3253 e8 3.5mm wnm aoz negwonaooow:5

EXAMPLE 62 parts of boric acid is mixed with 228 nylthio-ethanol and 78parts of 2- and 500 parts of toluene is added. The mi refluxed for threeand a half hours, durin 54 parts of water "is removed. The pro tionallydistilled The product boils at 121 to 125 C/0.05 mm. Found: B 3.6percent, S 30 percent, SH 10.7 percent. (CH CHSCH -CH 0) B-O CH,CH -SHrequires B 3.62 percent, S 30.6 percent, SH l0.5 percent. lf Example 2ais repeated substituting l.8 percent of the above boric ester for the1.8 percent of boric acid, ignition does not occur for 20 to 25 secondsand the burning time is only seconds.

Using 3.6 percent of the above boric ester the time to ignition is 25 to28 seconds and the burning time approximately l2 to 15 seconds. Theseresults show that the boric ester is superior to pure boric acid andother known additives (cf. Examples 3a and 3b) in flameproofingproperties as indicated by longer ignition times and shorter burningtimes.

By repeating Example 10 but using the starting materials and reactionconditions indicated in Table 2 there are obtained the new boric esterslisted in the second column of Table 2.

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CoVer Page, left hand column, insert 1 LBQ] Foreign Application PriorityData.

* vJan. 10, 1969 Germany. .P, 19 01 058.3

Signed and sealed this 2mm. day of April 1973.

(SEAL) Attest:

EDWARD M.F'LLETCHER,JR. ROBERT GOTTSCHALK Atte sting OfficerCommissioner of Patents

2. A boric ester as claimed in claim 1 and having the formula (CH2 CH-S-CH2-CH2-O)3 B.